Property and equipment consisted of the following at December 31, 2022 and 2021 (in thousands):


	2022			2021
Equipment	$	7,551,099		$	7,742,101
Oil and natural gas properties		236,156			229,403
Buildings		175,212			182,280
Land		23,610			24,562
Total property and equipment		7,986,077			8,178,346
Less accumulated depreciation, depletion, amortization and impairment		(5,725,501	)		(5,846,591	)
Property and equipment, net	$	2,260,576		$	2,331,755

Depreciation, depletion, amortization and impairment — The following table summarizes depreciation, depletion, amortization and impairment expense related to property and equipment, intangible assets and liabilities for 2022, 2021 and 2020 (in thousands):


	2022		2021		2020
Depreciation and impairment expense	$	472,969	$	818,999	$	644,943
Amortization expense		2,891		24,606		19,281
Depletion expense		8,085		5,573		6,686
Total	$	483,945	$	849,178	$	670,910

On a periodic basis, we evaluate our fleet of drilling rigs for marketability based on the condition of inactive rigs, expenditures that would be necessary to bring inactive rigs to working condition and the expected demand for drilling services by rig type. The components comprising rigs that will no longer be marketed are evaluated, and those components with continuing utility to our other marketed rigs are transferred to other rigs or to our yards to be used as spare equipment. The remaining components of these rigs are abandoned. There were no impairments in 2022. In the fourth quarter of 2021, we identified 43 legacy non-super-spec rigs and equipment to be abandoned. Based on the strong customer preference across the industry for super-spec drilling rigs, we believed the 43 rigs that were abandoned had limited commercial opportunity. We recorded a $220 million charge related to this abandonment in the fourth quarter of 2021. In the second quarter of 2020, we recorded an impairment of $8.3 million related to the closing of our Canadian drilling operations.

We also periodically evaluate our pressure pumping assets for marketability based on the condition of inactive equipment, expenditures that would be necessary to bring the equipment to working condition and the expected demand for such equipment. The components of equipment that will no longer be marketed are evaluated, and those components with continuing utility will be used as parts to support active equipment. The remaining components of this equipment are abandoned. In the fourth quarter of 2021, we recorded a charge of $32.2 million related to the abandonment of approximately 0.2 million horsepower within our pressure pumping fleet. The majority of these units were frac pumps but also included pump down units. These units were abandoned due to changes in customer preferences for dual fuel, advancements in technology, and prohibitive reactivation costs. There were no similar charges in 2020 or 2022.

We also periodically evaluate our directional drilling assets. In the fourth quarter of 2021, we abandoned certain directional drilling equipment totaling $2.5 million and recorded a charge on our developed technology intangible asset of $11.4 million due to advances in technology that rendered those assets, and their related spare parts inventory, obsolete. There were no similar charges in 2020 or 2022.